Sedgwick County and Wichita firefighters searched near the east shore of Lake Afton for about four hours Saturday after witnesses reported seeing a man go under the water shortly before 5 p.m.

Sedgwick County Division Chief Daniel Wegner said shortly before 7 p.m. that the man was presumed drowned. The search was suspended for the evening shortly before 9 p.m. Wegner said it will resume Sunday morning.

Firefighters used two boats with sonar and a pair of divers to searching the lake in depths of 6 to 10 feet. There was zero visibility in the water, Wegner said.

The man was last seen about 40 yards offshore, Wegner said. His disappearance came as Lake Afton, in western Sedgwick County, was crowded with people trying to escape the heat. Several witnesses said they heard the man’s family yelling for help and tried to rescue him. Among them were Joe Blaine, who is at the lake camping with friends, and Tyler Harrison, a 22-year-old lifeguard who was wake-boarding with family.

Blaine said he dove into the water several times, searching for the man "by touch only" along an underwater shelf near the area where fire crews were conducting recovery efforts.

"I kept diving and trying to feel around," he said. "We were all just doing what any human being would do."

Harrison said he was on a boat when others waved him over to help about three minutes after the man went under.

"A group of family members told us to look in the water for a swimmer who had gone underwater caused by the current," he said. "I dove in and used a life jacket, a rope and a buoy to look for him."

Firefighters had two boats in the water searching with sonar, and divers were searching the bottom of the lake in depths of 6 to 10 feet. There is zero visibility in the water, Wegner said. Sedgwick County sheriff’s deputies and county Emergency Medical Services were also on scene.

"My buddies and I tried our best," Blaine said. "It’s kind of a bad end to the weekend. We hope they find him."